Topic: 1959 lark 35hp questions – Antique Outboard Motor Club,Inc

This topic has 35 replies, 9 voices, and was last updated 2 years, 6 months ago by mark weaver.

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July 4, 2017 at 10:48 pm #7539
opposedtwin
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US Member
Wondering about the initial carb settings for this model. My notes say 1955 and up big twin/RDs is: low speed out 1 1/4 turns, and high speed out 1/3 turn. Anyone know for sure?

I went through the carb a year ago and it ran great. This year it’s great at wot, but when I idle it down, it dies when i try to increase the throttle. Regardless of whether I try to increase it fast or slow, it still dies. Seems certain it’s a carb (fuel delivery issue) but I will clean the points and re-set the timing with my timing fixture.

What might it be? I’ll check to see where the hs and ls needles are currently.

Scott
July 4, 2017 at 11:00 pm #60988
frankr
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Fuel saver rod on the side adjusted correctly?
July 4, 2017 at 11:10 pm #60989
opposedtwin
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US Member
Frank, is this the fuel save rod (#11)?

Not sure how to adjust. I’ll check my manual.

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July 4, 2017 at 11:19 pm #60990
chris-p
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Yes that is it.

In general, I start the needles at 1.5 and 3/4, and tune from there.
July 5, 2017 at 1:07 am #61001
frankr
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Judging from all the marks on the rod, somebody has tried adjusting it all over the map.
July 5, 2017 at 1:12 pm #61023
lindy46
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You most likely need to synchronize the carb to the magneto. First make sure the cam follower roller just starts to open the carb butterfly when the manifold pointer (just to the left of the roller) points to the mark on the cam. Adjust by loosening the throttle arm clamp screw and adjusting the eccentic screw to make it so. Once that is properly adjusted, rotate the armature plate to its’ full spark position and adjust the control rod collar (loosen the set screw) so that it almost touches the pivot pin (about 1/32-1/16" clearance). This should happen at about 2/3 throttle. Then tighten down the collar. Now, with the magneto fully advanced, further rotation of the throttle will push the follower roller away from the cam (via the fuel saver rod) until the carb butterfly is fully open.
July 5, 2017 at 3:04 pm #61029
outbdnut2
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US Member
Sometimes your problem of quitting when you increase the throttle off idle is as simple as turning the idle needle 1/4 to 1/2 turn richer than the leanest sweet spot.
July 5, 2017 at 8:06 pm #61041
garry-in-michigan
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Lifetime Member
A perfect idle in gear leans out with the increase in RPM when the propeller load is removed. (Shifting into neutral) The richer mixture will make it easier to start a cold engine. Any additional carbon deposits are usually eliminated by a high speed run. . . 😀
July 6, 2017 at 11:17 am #61088
bill-mcnamara
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Canada Member
Had a problem with the Fuel saver collar slipping yesterday on one of the twin Javelin’s I’m running. Turns out the collar is actually broken on its back side and was slopping, so will install another one. The engine starts perfectly, great compression & spark but was bogging down at higher RPM’s.
Found a good description of set up of Fuel saver Control, in the 10th edition of the Service Manual, page 162-3 if you happen to have a copy or can view the on-line version. Sorry, don’t have the link handy.
Will run them again today and see how it works.
Bill.
July 6, 2017 at 11:19 am #61089
bill-mcnamara
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Canada Member
ophs…that was "slipping" not slopping, sorry guys. Not enough Java yet this morning!
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